Hi Colin, afaik the red wire[very odd] is connected to the earth and the white or blue is connected to either side of the switch with the 12v feed in the centre, so your readings seem correct dependant on switch position.

as you have a multi meter test the voltage drop to earth, as unless it's connected to the frame it may get resistance perhaps through the bearings if the earth is connected to the handlebars etc.

they can be slow to heat but they do work well. initially i had them on the tenere [oxford hotgrips now, present] and now are fitted to my gasser. tho for some reason i have the white going to earth and the red and blue together recieving power via a switch. mucho heat.
I recall studying the circuit layout and coming to the conclusion as to gaining the most heat, it may invalidate the warranty of the grips but they are hanging in there and get proper warm. your call!

bernard